This is not certain, furthermore, I see no reason to condemn Foxconn(any manufacturer) more than Apple(any design company using said manufacturer). Apple could demand better adherence to US standards in the Foxconn plants making their products. Foxconn could just buck the local trend and treat their worker better than their rivals. Why does neither Foxconn nor Apple do this? Money. Foxconn can't do it and survive and Apple wants to maintain their 30% profit margin on their products.
However when you move the plant to the US things change. Foxconn MUST meet much more stringent working standards, not only because the US has more stringent regulations but they will not find workers to work in conditions similar to those in China. Finally, almost certainly what will happen is that the majority of the manufacturing work done in the US will be done by robots and only some small points will humans be used.
One thing that hasn't been addressed in the news thus far is how Foxconn might use the robotics expertise they gain from operating in the US in China. This could have a major effect on the Chinese economy and what that effect will be is far from clear (IMHO).